A wireless communications system uses paging messages on the paging channel or traffic channel to notify the access terminal (AT), also known as mobile station (MS), of incoming voice or data calls and to send other control information. To conserve power consumption, idle ATs wake up periodically during the assigned time slots to monitor the paging messages. In various evolutions of the third generation (3G) wireless communications system, a regular paging message is transmitted on the shared traffic channel with hybrid automatic repeat request (HARQ). Therefore, it may take a few interlaced frames for the ATs to correctly decode the regular paging message, which prolongs the wake-up time for idle AT, and shortens the standby battery time. To further conserve the power consumption, a quick paging channel (QPCH) is used to indicate if there is a regular paging message intended for an AT in the up-coming pre-assigned time slot. The use of a QPCH improves the battery life by enabling the idle ATs to avoid monitoring for a regular paging message if there is no regular paging message intended for this AT. Less power is required to monitor the QPCH than is required to monitor for a regular paging message.
False wake-up can occur causing the AT to monitor for a regular paging message when there is no regular paging message intended for this AT. The optimum design of the QPCH minimizes the false wake-up probability, thus, maximizing the battery life at the AT.
FIG. 1 illustrates a published proposal for quick paging message 10 designed for the air interface evolution (AIE) of cdma2000 technology, as documented as the Third Generation Partnership Project 2 (3GPP2) standard contribution C21-20060911-016. According to FIG. 1, header 100 in the quick paging message has a variable length and indicates the message format. If the number of ATs being quick-paged is larger than seven, a bitmap with variable times of hashing is used, while if the number of ATs being quick-paged is smaller than or equal to seven, the quick paging message is divided into header 100 and one or more quick page identifier (QPID) fields, each QPID field contains a certain number of the most significant bits (MSBs) of an AT's session seed. An idle AT will monitor the next regular paging message if it sees that the MSBs of its session seed match one of the QPIDs in the quick paging message.
According to the aforementioned published proposal, the numerical relationship among these QPID numbers in the sequence that they appear in the quick paging message is called the ordering pattern. Additional bits of the session seeds of the paged ATs, which are called ordering bits, can be indicated through implication by the ordering pattern and are evenly distributed among all paged ATs to increase the effective length of the QPID fields, thus, reducing the false wake-up rate. A method of bit-compression is also used for circumstances in which there are six or seven ATs paged, where, if the MSBs of two AT's session seeds match each other to a certain length, the part that matches can be indicated only once to allow additional bits to be evenly distributed among all QPID fields. This further increases the effective length of the QPID fields.
In order to transmit the ordering bits, the transmitter sorts out the ordering pattern by the numerical relationship among the partial QPIDs that are explicitly indicated in the QPID fields. It then uses a look-up table, and those additional session seed bits that are to be implicitly indicated by the ordering pattern, to determine the sequence by which the explicitly indicated partial QPIDs should be transmitted. The receiver, after receiving the quick paging message, also sorts out the ordering pattern by the numerical relationship among the explicitly indicated partial QPIDs. It then uses a look-up table to determine the values of those additional session seed bits that are implicitly indicated by the ordering pattern. The receiver forms each complete QPID by padding the additional session seed bit to the corresponding explicitly indicated partial QPID. Using this determined QPID, the receiver determines if it is being quick-paged by matching the MSBs of its session seed with each complete QPID. As the number of quick-paged ATs increases, the complexity associated with sorting the numbers and searching the look-up tables increases exponentially. Therefore, it becomes costly to implement such a method when the number of quick-paged ATs is larger than four or five.
The aforementioned published proposal claims to be able to extract the maximal number of ordering bits that is theoretically allowed. However, the maximal number of ordering bits can be embedded in and extracted from the ordering pattern only if all explicitly indicated partial QPIDs in the QPID fields are unique. When some explicitly indicated partial QPIDs are the same, the number of ordering bits that can be embedded in and extracted from the ordering pattern is significantly reduced. Additional look-up tables are to be provided in this case. Moreover, certain combinations of explicitly indicated partial QPIDs and additional ordering bits may not be accommodated by the transmitter, or else errors will occur at the receiver. For example, in the case with three paged ATs, A, B, and C represent three partial QPIDs that can be explicitly indicated in the QPID fields. If B=C, there are only three ordering patterns that the receiver can differentiate, namely ABB, BAB, and BBA, using B to replace C since B=C. The other ordering patterns cannot be allowed at the transmitter, or the receiver will decode the ordering bits incorrectly.
FIG. 2 illustrates another proposal for regular paging message 20 designed for the air interface evolution (AIE) of cdma2000 technology, as documented as 3GPP2 standard contribution C21-20060911-024. According to FIG. 2, a page record is used to address multiple ATs via a single regular paging message. Header 200 of the page record indicates how many ATs are being paged by the regular paging message. When paging one to four ATs, up to four 32-bit access terminal identifier (ATI) addresses 201-204 may be included in the record. When paging N ATs using one page record, where N is an integer greater than four and less than nine, the 128-bit page record is divided into N x-bit partial addresses for N ATs being paged, where x is approximately equal to [128/N]. Each partial address is based on certain numbers of the least significant bits (LSBs) of the AT's session seed. Additional session seed bits can be implied from the ordering pattern of the explicitly indicated partial addresses relative to the sequence that these explicitly indicated partial addresses appear in the page record, similar to the ordering bits in the quick paging method as described above and in FIG. 1. Again, the complexity of realizing the performance gain from the full ordering bits is high at both the transmitters and the receivers.